1. Field of the Disclosure
Embodiments disclosed herein relate generally to the alkylation of paraffinic hydrocarbon feedstocks. More particularly, embodiments disclosed herein relate to a process for the preparation of an olefin-containing feed and an alkylation process using the prepared feed.
2. Background
Alkylation is the reaction of paraffins, usually isoparaffins, with an olefin in the presence of a strong acid which produces paraffins, e.g., of higher octane number than the starting materials and which boils in the range of gasolines. In petroleum refining, the alkylation reaction is generally the reaction of a C3 to C5 olefin with isobutane.
In refining alkylations, hydrofluoric or sulfuric acid catalysts are commonly used. For sulfuric acid catalyzed alkylation, low temperature or cold acid processes are favored, minimizing side reactions. In a typical process, the reaction is carried out in a reactor where the hydrocarbon reactants are dispersed into a continuous acid phase.
For example, U.S. Pat. No. 2,762,853 discloses an alkylation process including feeding isoparaffins, such as isobutane or isopentane and C2-C5 monoolefins to an alkylation reactor. The alkylation reaction is catalyzed with sulfuric acid in excess of 88 percent, preferably in excess of 96 percent. The alkylation products are then separated into gasoline range components and heavier alkylate products.
As another example, U.S. Pat. No. 2,859,260 discloses an alkylation process including reacting isoparaffins with olefins in the presence of a sulfuric acid catalyst. The reaction product is then separated to recover a hydrocarbon-rich phase and an acid-rich phase. The hydrocarbon-rich phase is further treated to remove catalyst esters from the hydrocarbon phase, among other downstream operations. Another example of a prior art alkylation process is disclosed in U.S. Pat. No. 3,013,092.
Alkylation feedstocks, such as a fluid catalytic cracking (FCC) C4 cut may include numerous components, including n-butane, isobutane, n-butene, and isobutene. Undesired components in alkylation feeds may include oxygenates (such as water and oxygenated hydrocarbons, such as ethers and alcohols), dienes (such as butadiene), nitrogen-containing compounds (such as nitrites and amines), and sulfur-containing compounds (such as methyl mercaptan and ethyl mercaptan). The presence of these undesired compounds may result in increased acid consumption in both hydrofluoric acid (HF) and sulfuric acid (H2SO4) alkylation units.
Accordingly, there exists a need for processes to improve the performance of alkylation units, including decreased acid consumption.